Is Light The Future Of Classroom Networking?

(cc) matt512

Last year I purchased a 802.11n wireless router for my house. I really hoped it would be faster than my old one but I quickly realized that most of my neighbors also had routers and many of them were on the same radio channels. This interference slows the network down and it’s only going to get worse. If you are in an apartment complex it can be very difficult to get a good signal.

A cool new prototype was shown at CES recently. It used light pulses to transmit information to another device that used a camera to see the pulses. While slow, the technology has huge potential. The article talks about using LED lights that are starting to be used for general illumination as a carrier for this information. The authors of the article think this is a good idea, but what if you don’t need the lights on? I would think infrared bands would be more practical.

I do think this technology will be useful and can help provide high bandwidth in rooms with lots of people. (like classrooms)

AMONG the many new gadgets unveiled at the recent Consumer Electronics Show in Las Vegas was a pair of smartphones able to exchange data using light. These phones, as yet only prototypes from Casio, a Japanese firm, transmit digital signals by varying the intensity of the light given off from their screens. The flickering is so slight that it is imperceptible to the human eye, but the camera on another phone can detect it at a distance of up to ten metres.

Last October a number of companies and industry groups formed the Li-Fi Consortium, to promote high-speed optical wireless systems.

To turn a light into a Li-Fi router involves modulating its output, to carry a message, and linking it with a network cable to a modem that is connected to a telephone or cable-broadband service, just like a Wi-Fi router. Incandescent light bulbs and fluorescent tubes are not really suitable for modulation, but they are yesterday’s lighting technology. Tomorrow’s is the light-emitting diode. LEDs are rapidly replacing bulbs and tubes because they are more efficient. And because they are semiconductor devices, tinkering with their electronics to produce the flickering signals required for data transmission is pretty straightforward

Dr Povey’s group is already up to 130 megabits a second (faster than some older Wi-Fi routers) over a distance of about two metres

Specially constructed LEDs would be even faster. The Li-Fi consortium reckons more than 10 Gbps is possible. In theory, that would allow a high-definition film to be downloaded in 30 seconds.

Communication, though, is a two-way street. That means the LEDs involved in Li-Fi would need photodetectors to receive data. Some LED systems have such sensors already (to know when to turn on at night). But even if LEDs are not modified Dr Povey reckons hybrid systems are possible: data could be downloaded using light but uploaded (typically a less data-intensive process) using radio.